1. Field of the Invention
The present invention is generally related to a positioning system and method thereof, and more particularly to a system for positioning micro tool of a micro machine and method thereof.
2. Description of the Prior Art
With technological product worldwide moving to compact, ultra precision development, it is an increasing trend for the requirement of micro precision manufacture for 3C industry, optoelectronic device, semiconductor manufactures, communication industry, precision mould manufactures, and precision component manufactures.
Miniature manufacturing technology nowadays utilizes micro electronic device manufacturing technology that develops micro electromechanical systems (MEMS). Nevertheless, the MEMS technology shall be suitable for processing 2-2.5D geometrical outline, and relative processing precision (size tolerance/workpiece size) of that is about 10−1˜10−2 mm. For relative precision close to or larger than 10−3˜10−5 mm of larger processing mould, as well as complicated 3D miniature product, there is no solution or technology to meet such a requirement. Another bottleneck is that MEMS technology can not be applied to metal material or other diverse material. On the other hand, although nano-scale processing usually utilizes STM or AFM, they are low cycle time and immature. Hence, although MEMS technology (such as LIGA technology) developed tolerable application, miniature industrial component manufacturing method still using traditional mechanical processing, moulding, EDM, or LASER processing. Therefore, development of Non-MEMS miniature processing technology is a mainstream in worldwide study and research, which utilizes traditional mechanical processing, by means of miniature design and equipment, with meso-/micro-scale processing technology to approach precision processing. After such this field being continuously and extensively developed, it may exceed limit of MEMS technology, and applied to processing diverse metal material to extend to various industrial applications.
There are many savants and researchers worldwide devote themselves to study of precision research now. However, due to miniature precision processing, equipment for precision processing still needs considerable improvement in precision. Besides equipment design should keep in definite range, differing to medium or large size processing, requirement of processing precision is elevated while equipment size is minimized, even under the same relative processing precision (size tolerance/workpiece size) requirement. Therefore, besides precision to processing equipment per se, factors of precision processing, such as positioning deviation of a micro tool (diameter less than 0.1 mm) prior processing, deflection variation of the micro tool in processing, and vibration of the micro tool, are not ignored. Minimized micro tool and workpiece will incur increase of position difficulty. Micro workpiece shall incur position deviation while transferred by robot arm or manpower, or mounted on machine by jig. If such deviation can not be corrected, this will cause initial positioning error between micro tool and processing origin point of the workpiece, and processing precision can not be kept in standard requirement.
Generally speaking, initial processing error can be minimized by precisely positioning micro tool. While in processing, the error shall deviate the micro tool from theoretical processing position, and amount of deviation will depends on theoretical position. In order to diminish such positioning error, in conventional processing, operators must use tool to touch the workpiece in order to confirm relative position, and then continue to processing. Nevertheless in precision processing, due to volume and shape of a workpiece are tiny, the above mentioned issue can not be resolved by using conventional method. Besides, due to tiny micro tool, it is impossible and causes micro tool broken that relative position between micro tool and workpiece is positioned by using the micro tool contacting the workpiece. According to the above description, research points for promoting precision of precision processing may focus on examining positioning deviation between micro tool and workpiece before processing, correcting such a deviation, and automatically and exactly positioning micro tool to theoretical position on workpiece. Hence, development of positioning system for micro tool of micro machine is a critical objective in micro manufacturing industry. Besides, micro tool is easy deformable, difficult mountable, and unavoidable generating positioning deviation on assembly and detachment to micro machine, the positioning system needs in-line inspection, non-contacting, and low cost in considering applicable to industry. Many efforts have been devoted to research and development of precision processing equipment nowadays, but seldom report including all three characters to upgrade micro milling/drilling precision is reported. This invention will inspect positioning deviation of a micro tool, with automatic function of positioning the micro tool to correct position error, such that micro tool can be placed immediately and exactly on the theoretical location, and applied to precision processing industry.